A contact image sensor (CIS) is a most common optical sensor used in a device for recognizing and verifying banknotes. The CIS is normally used to recognize a denomination of a banknote, front and back sides of the banknote, and used to identify authenticity of the banknote. Multiple sections are spliced inside a currently common CIS. Due to factors such as fabrication and the splicing process, there are discrepancies among light-sensitive units in various sections of the CIS, so various sections of an original image directly collected by the CIS are different in brightness, which affects the recognizing the banknote and identifying authenticity of the banknote performed by the device for recognizing and verifying banknotes. Thus the original image collected by the CIS needs to be compensated and corrected.
In a conventional systematic solution, the compensation and correction for the original image collected by the CIS is generally performed by a micro control unit (MCU) in the device for recognizing and verifying banknotes. Since the MCU also manages main tasks such as a banknote recognition algorithm, and information communication as well, a system performance of the MCN may be affected if the MCU spends too much time on compensation and correction for the CIS, thus affecting operation efficiency of the device for recognizing and verifying banknotes.
Therefore, a solution for improving the system performance of the MCU while ensuring the MCU to compensate and correct the original image collected by the CIS is highly required.